Launcher used in self defense are usually between 38 mm and 56 mm for law enforcement units or military forces and in some countries non lethal bullets are sold for public use in 12 gage caliber (around 19 mm), the penetration effect of such a projectile is generally greater for the smaller caliber at the same energy. In the state of the art the following patents are describing deformable or crushing heads with some controlled or limited force during impact FR 0802536, FR0900303 or WO2009FR00520 and the latest FR2950688. Said patent are describing realization of projectile using a head fastened to an holder which is resistant enough to engage the riffling and produce the rotation of the projectile in order to enhance the trajectory by gyroscopic effect. Those patent never describe the protection or confinement of the head, which should be smaller than the caliber to avoid friction and projectile deformation inside the barrel.
It is known from another patent of same inventor that the use of foam material or microstructure, especially of the polyphenolic or polycarbonate foam type used to get materials that absorb projectile energy with the projectile auto destruction by shearing of constitutive elements of the microstructure cells during the impact. It is also known by another said patent, that the use of foam material or microstructure of aluminium allows to get a progressive consumption during an impact by buckling of the alveoli walls or elements of the said foam or microstructure. These two types of structures to limit force to impact speeds and realize good attenuation of damage to the target but have advantages and disadvantages. The association of these two types of structures can be achieved in the present invention in order to make it more gradual and uniform on the impact area to reduce the maximum stress generated by the projectile on the target and seeking to increase the expansion of the impact with speed of the projectile. An industrial way to achieve that is to use a honeycomb open cells material type like a honeycomb with thin walls or an deployed aluminium structure which could be included in polymerized foam during manufacture.
The achievements of under calibrated projectiles for applications of hunting or military lethal are known as sold under trade marks like Sauvestre or FIER, these achievements are intended to bring greater speed of output, a flatter trajectory autorised by the structure of the projectile on trajectory after separation of the shells as for the Sauvestre bullet that is a civilian version of the so-called arrow and described in the patent FR19940012835 19941026 ammunition. The J P. Denis patent describes a mode of realization of a lethal munition under calibrated without separation on trajectory, which allows to get different behaviors of the ammunition in penetration on different types of materials or living bodies and also of strongly alter the aerodynamics and so the trajectory of the projectile and its kinematics. The shell used in this type of project is not fragile to the impact and may even play a role depending on the type of target encountered. It is on the achievements of aforementioned projectiles under calibrated in a way to produce lethal projectiles which is precisely the reverse of our goal: for lethal purposes, they need to reduce the projectile diameter to facilitate perforation or deeper penetration, reduced diameter also allows an improvement of the lengthening of the projectile and enhance its flight capacity for some specific applications.
Non-lethal projectile using a sliding jacket which allows a symmetrical launch without deformation of the projectile and which nevertheless fragile at impact in order not to modify terminal ballistics is new for the state of the art. Current achievements are describing a cylindrical body or head with an capacity of shock absorption and expansion. Most of such projectiles or head are constituted by foam material or alveolar structure with specific properties: fragile or breaking on impact; elastic or deformable way reversible or not. This front part is generally fixed or linked to a rear hard plastic part which is designed to take the riffling of the barrel, and essentially to support the thrust of the combustion gases during the shooting phase. The main aerodynamic default of those said low lethality projectile or claiming it, is the bad equilibrium in flight because the center of application of aerodynamic forces, is located in front of the centre of gravity of the projectile. Then the difficulty to balance it forward does not result from a misunderstanding of the man of the art in aerodynamics, but is related to the absence of a known design which could allows to realize it in an industrial way without generating disadvantages like the destruction or deformation of the shot during the launch or its immediate flight destabilization. In case of unsufficient stabilization by gyroscopic effect, most of the known projectiles have a strong tendency to destabilize on trajectory. Said unstabilization making the hard plastic holder coming forward to have a direct impact on the target with lethal effects or severe physiologic injuries. This defect is corrected according to the invention by the use of a rear soft tail nevertheless able to sustain the shooting burst and hot gazes, this tail can typically be made up of low density polyethylene, we can also use of the polyvinyl vinyl, or polyurethane containing the plasticizer or polyimide with a sufficient proportion of plasticizer to lower their point of glass transition below the temperatures specified for the use of the device according to the invention.
It is of great interest to develop for riffled barrels weapons a projectile which will not have a hard plastic holder to manage the launching pressure or to reduce this holding part to a simple cap in order at first to push forward the center of gravity of the projectile and improve its stable trajectory and on secondly to avoid the holder impact on target, which could occurs even with slight incidence. The main advantage according to the invention for rifled guns projectile is to get more than 60% of the projectile mass having both absorption and expansion capacities, where current projectiles actually have between 60 and 90% of the mass concentrated in a dangerous plastic part, said plastic holder could be lethal at impact for receiver if he is not protected by a helmet or a protection jacket. For smooth barreled launchers, there is an interest in developing a munition that retains the benefits of expansion to the impact such as the Bliniz, while providing the opportunity to realize stable path like an arrow and that enable smooth bore launcher to compete with rifle barrels law and order launchers.
Finally almost all projectiles marketed according to the State of the art are of restricted or prohibited usage below a certain distance due to the fact of their potential attrition if they went unstable on trajectory. So there is an interest in developing a precise and stable projectile for close range to long distance but whose softness and the force limitation at impact allows to use it from short distance; the best results will be obtained if one can also adapt the output speed of the Launcher depending on the distance of the target. The physical action of the projectile at impact according to the invention is to provide a strong deformation of the envelope that must be very soft and elastic, such soft material shows in compensation a very large coefficient of friction that is typically close to 80 or greater. With such material, contact between the soft head part and the barrel of the weapon will be asymmetrical and destructive. The projectile realization up to the inventor, allows to design a projectile very close in diameter with the caliber of the weapon and nevertheless, the contact surface with the launcher tube could shows very low friction coefficients and can especially be below 0.1 millimeter thick. Due to the fragile behavior of the jacket in dynamic conditions, it will break at impact and will not modify the terminal ballistic of the projectile head.
The realization of projectile which delivered limited force onto the target requires first of all to maintain the integrity of said projectile during the launch phase, on this aspect the present invention provides an answer since the sliding sheet (3) ensures the symmetrical gliding of the ogive in the launch tube and preserves its integrity of form until the impact while composition material is much more deformable and soft than the usual projectiles. One of the answers already given to the limitation of the lethality is to allow a strong expansion either by using elastic envelopes and contents in the form of particles, in particular like BeanBag and Bliniz described in the patent U.S. Pat. No. 6,302,028 or in the patent FR0900303 supra.
The projectiles described in these patents are not practically feasible without compromise between accuracy and low lethality; indeed, the search for the best spreading is going through the greatest possible elasticity and low hardness of the envelope or outer skin of said projectiles, such embodiments are caused to deform during the propulsion phase or even during the ballistic flight, such effects is known on the “Bliniz” which is able to provide heavy shock with limited penetration, but with a poor precision due to the aerodynamic flight deformation. The answer unveiled from the present invention makes possible not only to avoid the deformation of the projectile during the launching phase, but also to use simultaneously in the same projectile such microstructures and divided states of the material in a structure which will make possible in the same time, first not to be altered during the launching phase but also to ensure both the aerodynamic behavior and the limitation of the maximum force applied to the target by a better distribution of the stresses. The rigid foam providing a dynamically fragile structure of the core is quite complementary by nature with the fine divided particles inside an elastic content, because those particles are making during the impact a more important increase of the stress in the center of the impact and these are the radial components of the transmission of reaction this central impact to each of the grains that causes the spreading, presence of foam or soft elastic material in front of this divided particles bag will make a spreding in time of this centered impact energy.
Energy absorption in the present description is the dissipation of energy in a non-reversible destruction or deformation process; that is to say, when the applied force disappears, said deformation remains without any energy restitution effect, in fact this projectile structure achieve a quite perfect mechanical soft shock. At the contrary, the application of a force or the supply of mechanical energy during an impact on an elastomeric foam or elastic rubber projectile leads to a high compression which shows, at the end of the impact or application of the force, a mechanical restitution in the form of for example rebound, which is detrimental to the desired goal of delivering the energy of the projectile to the target.
If we take a conventional projectile, whose operational purpose is the law and order enforcement and which claims a mitigation of the lethality at the impact, as marketed or described in the existing patents, we always find a bouncing part of mechanically elastic, and especially at a significantly high speed, hence a potential threat while it rebound. The examination of the state of the art thus shows that two types of projectiles are available which are more or less lethal according to the energy and the zone of impact and marketed in the category of non-lethal kinetic projectiles according to the type of weapon in which they are fired.
First, it is known projectiles adapted to the rifled guns that are made with a rigid plastic holder or base which has the first function of taking the riffling or grooves of the barrel in order to ensure stabilization of said projectile by rotating and gyroscopic effect on its trajectory. Due to the hard plastic material used, this part must be of resilient material and little deformable to impact, such a projectile is therefore potentially very dangerous if it arrives on this rear part because of its low deformability and its low capacity to absorb a part of the energy of impact shock due to its physical modification (destruction, deformation, modification of molecular bonds).
Secondly, there are projectiles adapted to smooth-bore weapons which can be divided into two groups: the first group encompasses the stabilized projectiles; such stabilization could be made by a tail on their rear part. These elements are usually made of hard material and not very deformable, therefore, even if they are lighter and thinner than the holder or riffling ring of riffled weapons, they do not participate in the absorption effect nor spreading shock at impact; the second group is formed with short-range projectiles which claim a large area of impact. They are generally characterized by a bad aerodynamic form factor. In this category, we can put all known deformable projectiles with solid content or achieving a great deformation at impact like the “bean bags” or “Bliniz™” for example as well as the projectiles working in elastic compression at impact like that of the “flash ball” of the company “Verney Carron”. It can thus be seen that the projectiles currently proposed are either potentially dangerous at impact or have aerodynamic characteristics which limit them to limited uses at short firing distances.
The known existing deformable projectiles have in addition a poor friction coefficients, typically higher than 0,5 on a metallic barrel, and at the same time make a projectile dissymmetry and slow down the departure if they came into contact with the gun. In particular this point is well established with a rubber envelope whose coefficient of friction on steel is known to be between 0.3 and 0.5 in static, and the friction coefficient that will be relevant for the dynamic launching phase is rather established around 0.8. We obtain then, that, if the deformation of the projectile is not perfectly symmetrical, which is almost the case, such projectile will be subject to a destabilizing force at the exit of gun, with a severe consequence on external ballistics by causing a tumbling, or nutation movement in the case of a projectile stabilized in rotation by gyroscopic effect. In order to avoid this contact, it is appealing according to the state of the art is a belt stripping grip for those driven in rotation or it is avoided that the deformable part of the head touches the core of the barrel for smooth-core launchers by reducing the diameter of the rubber or polymer head, which increases the level of stress per unit area applied to the impact area of the target.
For specific projectiles for smooth bore launchers, a sabot is then used to protect said projectile from the flames or burst of ignition, in order to collect the acceleration and facilitate its sliding, such embodiment is shown by “flash ball” projectile of Verney Carron company which uses an enveloping shoe Other deformable kinetic projectiles of 38 or 40 mm could also be found, using a fire-resistant holder or sabot equipped with a riffling ring for riffled weapons.
The operational need for a low lethality projectile that is easy to produce industrially can be reduced to the problem of having a highly deformable projectile during an impact and having a minimum of hard or harming parts, nevertheless designed so that it can withstand without modification its characteristics during the launching phase, and remains intact in shape and structure during the ballistic phases of flight, while being propelled with a minimum of friction during the launch phase. In order to be less harmful, the solutions are known and described in the state of the art since it is to use in contact with the target materials capable of large deformations or dispersion in an elastic content, the problem unresolved is how to succeed in preserving a form integrity to these soft or highly deformable composite assemblies, their deformation being according to random always dissymmetrical and thus degradating the ballistics. Such aim has to be withstand without enclosing said projectile in a hard shell. Solving problems concerning the symmetric sliding and reduced friction at the launching associated with the integrity of the projectile on trajectory are at first glance contradictory with the elastic deformation needed on target for a good terminal effect like those shown by soft and adherent projectiles.